Pigmented coating compositions are useful for their aesthetic as well as protective features. Such compositions contain a film-forming resin and a pigment dispersed in a liquid carrier. It is important that the pigment be satisfactorily dispersed throughout any film which results from the application of the coating composition. Therefore, it is desirable that the pigment be well dispersed throughout the liquid coating composition. Typically, the pigment in a coating composition is first dispersed with a polymeric resin referred to as a pigment grind vehicle or pigment dispersant. The resulting dispersion is then mixed with the film-forming resin of the coating composition and any other necessary components to produce the coating composition.
The use of amine functionality in pigment grind vehicles is well known. For example, U.S. Pat. No. 3,940,353 describes incorporation of small amounts of unsaturated amine group-containing monomers into polymer solutions to give improved pigment dispersants. Similarly, U.S. Pat. No. 4,302,560 describes incorporation of amine or amine salt functionality into a pigment dispersant. One common manner of incorporating amine functionality into an acrylic pigment dispersant has been to react a nitrogen-containing compound, such as an aziridine, with some of the carboxylic acid groups of an acrylic polymer. For example, aziridine compounds, such as ethyleneimine or propyleneimine, can be reacted to provide the amine functionality. However, the toxicity of ethyleneimine and propyleneimine has made this route undesirable. Consequently, an acrylic grind vehicle having amine functionality provided by means other than imine chemistry has been sought.